1. Field of the Invention
The present invention relates generally to medical devices and methods. More particularly, the present invention relates to apparatus for accessing vascular lumens and methods for clearing vascular lumens of occlusive materials.
Removing occlusive materials from the vasculature and other body lumens is the objective of many medical procedures. Obstructive materials in the vasculature include plaque, thrombus, embolus, clots, and fatty deposits. To remove such occlusive materials, catheters may be inserted into the occluded artery or vein for opening or removing the occlusive material. Of particular interest to the present invention, procedures commonly referred to as thrombectomy or embolectomy use a balloon-tipped catheter which is inserted into a blood vessel, either percutaneously or via a surgical cut down, where the balloon is advanced to a position distal to the obstructing material. After inflating the balloon, the catheter is drawn proximally to dislodge the material and remove it from the blood vessel. In some instances, a second sheath or catheter is introduced coaxially over the balloon-tipped catheter in order to apply suction and help remove the occlusive material before it is drawn out of the blood vessel.
When performing such thrombectomy or embolectomy procedures, the balloon-tipped catheters and other auxiliary tools may be introduced through a sheath which is positioned through a percutaneous tissue tract to allow access to the blood vessel. In addition, other auxiliary sheaths and tubular catheters may be employed and other aspects of the thrombectomy, embolectomy, or other vascular procedures.
While very effective, thrombectomy and embolectomy procedures sometimes have difficulty dislodging and removing certain occlusive materials from certain types of vessels. For example, the use of thrombectomy for removing plaque, clot and other occlusive buildups in arterio-venous grafts (AVG's) and arterio-venous fistulas (AVF's) can be particularly problematic. For example, a plug of occlusive materials frequently forms at the anastomosis site between the artery and vein, or artery and graft, and can be very difficult to remove. Moreover, the access sheaths and capture devices used in such procedures are not always optimal.
For these reasons, it would be desirable to provide improved methods and apparatus for performing thrombectomy and embolectomy procedures. It would be particularly desirable if such catheters and devices could improve the capture of clot, plaque, and other occlusive materials from AVG's and AVF's. Improved sheaths and other auxiliary devices for performing those procedures and others would also be desirable. At least some of these objectives will be met by the inventions described below.
2. Description of the Background Art
Thrombectomy devices employing aspiration are described in U.S. Pat. No. 6,292,633; U.S. 2002/0169436; U.S. Pat. Nos. 7,141,045; 7,033,344; 6,544,276; 7,578,830; 6,695,858; 6,210,370; 5,102,415; and 5,092,839. Catheters and sheaths having self-expanding regions are described in U.S. 2010/0131000; U.S. 2007/0135832; U.S. Pat. Nos. 7,799,046; 7,410,491; 6,511,492; 6,159,230; and 5,971,938.